/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Tencent is pleased to support the open source community by making behaviac available.
//
// Copyright (C) 2015 THL A29 Limited, a Tencent company. All rights reserved.
//
// Licensed under the BSD 3-Clause License (the "License"); you may not use this file except in compliance with
// the License. You may obtain a copy of the License at http://opensource.org/licenses/BSD-3-Clause
//
// Unless required by applicable law or agreed to in writing, software distributed under the License is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and limitations under the License.
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#ifndef _BEHAVIAC_BASE_META_ISDERIVED_H__INCLUDED
#define _BEHAVIAC_BASE_META_ISDERIVED_H__INCLUDED

namespace behaviac
{
    namespace Meta
	{
		namespace Private
		{
			template <typename BASE, typename DERIVED>
			struct TypeResolver
			{
				template <typename TYPE>
				static Yes ResolvedType(DERIVED const volatile *, TYPE);
				static No  ResolvedType(BASE const volatile *, int);
			};

			template<typename BASE, typename DERIVED>
			struct IsDerivedInternal
			{
				struct TypeCaster
				{
					operator BASE const volatile *() const;
					operator DERIVED const volatile *();
				};
	            
				static const bool Result = (sizeof(TypeResolver<BASE,DERIVED>::ResolvedType(TypeCaster(), 0)) == sizeof(Yes));
			};
		}


		/// Lets you determine if a type derives from another one at compile time.
		/*! IsDerived<A, B>::Result will be true if type B inherits from type A.
		 */
		template<typename BASE, typename DERIVED>
		struct IsDerived : public BooleanType<Private::IsDerivedInternal<BASE, DERIVED>::Result> 
		{
		};
	}//namespace Meta
}//namespace behaviac

#endif//_BEHAVIAC_BASE_META_ISDERIVED_H__INCLUDED
